


Establishing Baseline

by ScreechTheMighty



Category: Daredevil (TV), Marvel Cinematic Universe, The Avengers (Marvel Movies)
Genre: AU from the end of Age of Ultron, Devoid of Context, Drabble, Gen
Language: English
Status: Completed
Published: 2015-05-03
Updated: 2015-05-03
Packaged: 2018-03-28 18:51:32
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,083
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3865876
Author URL: https://archiveofourown.org/users/ScreechTheMighty/pseuds/ScreechTheMighty
Summary: <blockquote class="userstuff">
              <p>Pietro Maximoff isn't like other people. For starters, his heart beats way too damn fast.</p>
<p>(OR a completely contextless drabble based around a massive "crossover" AU I've been thinking about a lot lately.)</p>
            </blockquote>





	Establishing Baseline

**Author's Note:**

> This is dumb, but I wrote it anyway. Basically, Matt is hanging out with the Avengers because reasons and he manages to become friends with everyone. Including the speedster, because I said so.

The first time he heard Pietro Maximoff, he was seriously concerned that the Avenger was about to have a heart attack.

His heart was _racing,_ the way hearts usually did for the first few moments after someone stopped running. Except it wasn’t a few seconds; it was constant, _tha-thumptha-thumptha-thumptha-thump._ There was no way he should’ve been able to function with his heart beating that fast.

Bruce told him later that Pietro’s heart was always like that—it was a natural part of his abilities. Fast metabolism, fast heart. That didn’t stop it from sounding worrying.

The heartbeat caused another problem. All of Matt’s tells were related to the heartbeat of a normal person. He didn’t know what lying, surprise, fear, or any emotion sounded like in a heartbeat that was at least twice as fast as normal. Pietro was an enigma. Matt wasn’t sure he liked that.

And, of course, Tony had to go and _blab_ about it to Pietro. Fortunately, the kid was good-natured enough to ask Matt about the limitations to his lie detecting, rather than immediately exploiting it.

“You really cannot tell?”

“Not _yet._ ” Matt could hear Pietro’s racing heart from the other side of the room. He seemed to be perched on one of the tables near the window, rather than using the chairs. “I haven’t established a baseline for your heartbeat. Once I do that, it’s just a matter of hearing the differences.”

That was another thing about Pietro: he was always moving. Matt could hear the creak of the table shifting as he fidgeted, one leg jiggling, hand tapping against his knee. “How fast do I sound to you?”

“Like your heart’s about to pop. You're kind of unnerving.”

“Mutal feeling, _Diavol._ ” Pietro chuckled. “You people are so _slow._ How can you stand it?”

“We get by.” Matt took a second to listen to that racing heart again. “How long have you been like this?”

He heard a slightly rustling of fabric that he took to be a shrug. “Almost as long as I can remember. When did you lose your sight?”

The twins could be refreshingly blunt. Matt appreciated that. Tact was nice, but too much of it and he started feeling like someone’s delicate china. “When I was nine.”

“And can you remember what it was like seeing?”

“A little, sometimes. But most of what I remember is being blind.”

“It is the same for me. I wasn’t always fast, but it feels like I was.” He was still, for a second, then the creaking resumed. “Can you tell if Vision is lying?”

“Actually? I can.” No one was more surprised by this answer than Matt. “He doesn’t have a heartbeat, but I can hear the mechanical parts moving. When he lies, he hums, like a laptop fan. It's like I can hear the gears grinding as he tries to think of the most convincing way to word it.”

Again, Pietro chuckled. “He hates that, doesn’t he?”

“He’s impressed, but I’m sure the novelty of it will wear off quickly. It usually does.” Matt wasn’t sure what put the thought in his head; he was even less sure what drove him to voice it aloud. “Would it be all right if I listened? To your heart, I mean. I keep thinking, it might help if I can hear it more clearly…”

_Because that’s not an invasion of his personal space._

“…I’m sorry, I don’t know…”

The table creaked one last time, and the next movement Matt heard from Pietro were his approaching footsteps—light, almost bouncing across the floor. “Why not? Cannot hurt.”

If Matt didn’t think that Pietro was an all right kid before, he certainly did now. Matt stepped forward until he was close enough that he could lean forward and press his ear against Pietro’s chest. “If it starts feeling weird,” he said, “let me know, and I’ll stop.”

He could feel the shrug, muscles shifting, bones moving. Pietro’s voice rumbled against his cheek: “Knock yourself out.” The only sounds after that were the soft in-out, in-out of his breathing (a bit faster than usual, but not so much that it was alarming), and the racing of his heart and pulse.

_Tha-thumptha-thumptha-thumptha-thump._

Matt pressed a hand against his own chest and tried to time the rate of Pietro’s heart to the rate of his own. Once the initial shock faded, it was actually kind of nice to listen to. Oddly soothing. If he mentally slowed it down, Matt was almost sure it was the heartbeat of someone in good humor, alive and happy. Baseline. _Tha-thumptha-thumptha-thumptha-thump…_

“Uh, what are you doing?”

_Thathumpthathumpthathump tha-thumpthat-thump…_ A skip. Pietro was surprised. And so was Matt; he’d actually been so focused on Pietro’s heart that he’d missed the sound of someone walking into the room. Tony Stark, judging from the voice and the smell (grease and expensive cologne). “I’m calculating Pietro’s baseline heartbeat,” said Matt calmly. “You’re breaking my concentration.”

“Yes, Stark, you are breaking his concentration.” There was a laugh in Pietro’s voice. You didn’t have to be Matt to hear it. “Is there a problem?”

“You…both do realize how this looks, right?”

Matt smirked as he leaned away from Pietro. “No, Tony, I don’t have any idea how this looks.”

“I…” Tony huffed in annoyance. Pietro full-on laughed, almost drowning out the slight, embarrassed skip in Tony’s heart. “You know what I…you know what? Be that way. I don’t care.”

Matt waited until Tony’s  steps had retreated to a safe distance before he started laughing, too. “He’s never going to let us live that down.”

“Let him talk.” Matt hear a rustling of hair and fingernails against skin—Pietro scratching his scalp. “This is not the weirdest thing happening in this place.”

“Right. I think the Norse god wandering around beats me listening to your heart. And thank you for that, by the way.” Matt smiled. “It helped.”

“You’re welcome. Although you should know, it won’t do you much good. I am not fond of lying. I’ve been told I’m no good.”

“I guess we’ll find out.”

It took Matt a few more days to completely establish a baseline for Pietro’s heartbeat. And the first time he caught him in a lie—an innocent-voiced claim that he had _no idea_ where the rest of the takeout had gone, did you try asking Banner?—it was obvious as the nose on his face, or so the saying went.

_He really is bad at this._

**Author's Note:**

> The relationship name for this is Speed Demon.
> 
> ...I'll see myself out.
> 
> (Also the SPOILERS ~~pietrobeingalive~~ SPOILERS bit isn't the only part of this that's AU. I have a few more ideas that change the twins' backstories as we see them in AoU. Part of that is that they were always genetically predisposed to their abilities, and HYDRA's experimentation just made them stronger faster than they might've been otherwise.)


End file.
